1. Field of the Invention
This invention relates to a data-imprinting apparatus that is incorporated into a lens-equipped film unit in order to imprint light representative of the date, for example, onto the exposure screen of the photographic film. The light representative of the data is created by using either external light or an imprinting light source.
2. Description of the Related Art
Lens-equipped film units built into a unit body with a built-in shooting mechanism are known. These film units afford ease of photographing at any time. Among the lens-equipped film units, one with a data-imprinting mechanism is proposed in the OFFICIAL GAZETTE FOR PATENT APPLICATIONS H5-289164 (1993). The data-imprinting mechanism described in the GAZETTE functions as follows: when shooting is complete, by setting a desired date using a dial-type manual data-operating unit that is provided on the back of the body, a data-imprinting shutter component is actuated in interlock with the photographing shutter vane. This directs the natural light entering from the window at the front of the body to the backside of the cover through the lightguide, so that the date is imprinted on a contact basis onto the exposure screen from the backside of the photographic film through a data-imprinting plate on which a reverse-image (transparent) date is displayed.
The lens-equipped film unit described in the GAZETTE requires the manual actuation of the data-imprinting operation unit for each photographing date, which can be cumbersome. Therefore, it is desirable to incorporate a data-imprinting mechanism wherein a clock circuit with a pre-stored calendar is provided in the lens-equipped film unit so that the display can be updated automatically.
Data-imprinting devices that are used in most cameras (as distinct from lens-equipped film units) contain external display units that allow the user to check the date to be imprinted, and external operation units that allow the user to change the displayed date. Should the time data (date) in the clock circuit return to the initial value in the calendar or display an unreliable or a totally invalid date due to a temporary shutoff of the electrical supply to the clock circuit, due to vibrations or a battery replacement, for example, one can manipulate the external operation unit by looking at the external display and change the display status of the clock circuit to the correct date.
In contrast, lens-equipped film units, after being used, are sent to a developing shop together with the exposed photographic film. After the exposed photographic film has been removed, the film units are returned to the manufacturing plant for recycling. Because they are used only for a limited period of time as compared with an ordinary camera, and because they are low-priced, from a cost-reduction standpoint any data-imprinting apparatus used in such a lens-equipped film unit does not contain any external display units or operation units.
However, if external display units for monitoring or external operation units for correcting the time-keeping action of the clock circuit are omitted from a built-in data-imprinting device in a lens-equipped film unit, any fault that occurs in the data-imprinting device goes undetected with the result that the incorrect date is directly imprinted onto the photographic film.
Causes of a fault occurring in a data-imprinting device include: the lens-equipped film unit being subject to vibrations, as noted previously, resulting in a temporary interruption of the electrical supply to the built-in clock circuit in the data-imprinting device; external noise such as static electricity; and the intrusion into the clock circuit of strobe-recharging or flashing noise that is generated from the strobe circuit board that is incorporated into the film unit. In all cases, these problems lead to the resetting of the clock circuit, reverting the time data to the initial data, or cause a malfunction of the clock circuit resulting in an incorrect date display.
An object of the present invention is to prevent the imprinting of incorrect dates in a data-imprinting device that does not contain external display units for monitoring or external operation units.
To solve the above problems in a data-imprinting apparatus for a lens-equipped film unit that is provided with a clock circuit that keeps time by receiving electricity from a battery incorporated in a lens-equipped film unit containing photographic film, and a liquid crystal display element that displays date characters based upon the time data supplied from the clock circuit, such that the apparatus imprints the date characters displayed on said liquid crystal display element by means of external light that enters the film unit in conjunction with a shutter release operation, the present invention adopts the following structure: a data-imprinting apparatus for a lens-equipped film unit comprising: a detection means that detects any temporary interruption of the electrical supply from the battery to the clock circuit after the clock circuit has started keeping time; and a data-disabling means that, if a temporary interruption of the electrical supply is detected by the detection means, the liquid crystal display element is maintained in a non-displaying state so that no date characters will be imprinted onto the photographic film.
Among the data-imprinting devices that are known is one which is equipped with an imprinting light source that lights in conjunction with a shutter releasing operation, instead of the use of external light which falls incident upon and in conjunction with a shutter-releasing operation. The date characters displayed on the liquid crystal display element are imprinted onto the photographic film through the use of the light from the light source. In the case of a data-imprinting device of this configuration, the data-disabling means of the present invention disables the light source from lighting when a temporary interruption of the electrical supply is detected instead of maintaining the liquid crystal display element in a non-display state.
In the data-imprinting device of this configuration in the present invention, the lens-equipped film unit into which the device is incorporated has a limited useful life. Further, it suffices to simply imprint the date onto the photographic film. Therefore, the operation unit for modifying a date display can be provided inside the lens-equipped film unit such that the activation of the operation unit can be commenced when the device is shipped from the factory, so that the time-keeping operation of the clock circuit is started. Subsequently, and until such time as it is returned to the factory, i.e., during its period of use, if there is a temporary interruption of the electrical supply from the battery contained in the lens-equipped film unit to the clock circuit, the event is detected by the detection means. As a result, the data-disabling means holds the liquid crystal display element in a non-display state. Consequently, the present invention can prevent the imprinting of any incorrect date display. In devices that are equipped with an imprinting light source the imprinting light source is disabled from lighting, which also prevents the imprinting of any incorrect date display.
The data-imprinting device of the present invention comprises, in addition to the aforementioned detection means, or in place of the detection means, an initial data retention means that retains the initial data for the clock circuit, and a comparison means that compares time data from the clock circuit with the initial data such that if the comparison means determines that the data is in agreement with the initial data then the data-disabling means ensures that no date characters are imprinted onto the photographic film.
According to this configuration, if the clock circuit is accidentally reset due to a temporary interruption of the electrical supply to the clock circuit or if the clock circuit is reset by the intrusion of external noise such as static electricity or due to an internal noise that is generated when the strobe is recharged or when a flash is actuated, such resetting actions can be detected. Consequently, the present invention can prevent the imprinting of any attendant improper date display onto the photographic film.
As described above, the data-imprinting apparatus of the present invention, upon detecting that an interruption of the power supply to the clock circuit has occurred, holds the liquid crystal display element in a non-display state. In a configuration in which an imprinting lamp is provided, any subsequent lighting of the imprinting light is disabled. Therefore, the present invention can prevent the imprinting onto the photographic film of the clock contents of a faulty clock circuit that is caused by a temporary disruption of power supply.
Furthermore, the data-imprinting apparatus of the present invention, upon detecting that the clock circuit has been reset and its clock contents have been initialized, holds the liquid crystal display element in a non-display state. In a configuration in which an imprinting lamp is provided, any subsequent lighting of the imprinting light is disabled. Therefore, the present invention can prevent the imprinting onto the photographic film of the clock contents of a clock circuit that has been reset because of an external noise, for example.
Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings.